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| Illustration 1 | g00525035 |
Steering motor (1) Shaft (2) Seal (3) Case (4) Retaining ring (5) Seal (6) Shims (7) Barrel (8) Center pin (9) Shims (10) Port plate (11) Flushing valve (12) Piston (13) Retaining plate (14) Bearing (15) Bearing (16) Head (A) Port for the drive end (B) Port for the drive end (C) Case drain | |
The steering motor is a bidirectional fixed displacement piston motor. The steering motor is operated by high pressure oil from the steering pump. A change in the direction of oil flow through the steering motor does not change the amount of output torque from the shaft of the steering motor.
The steering motor is located in a horizontal position on top of the center housing. The center housing is located between the two rear axle housings. The direction of the steering motor's rotation determines the direction of the turn of the machine. The rate of the rotation determines the speed difference between the belts.
Oil flow through the steering motor can be in either direction. A change to the direction of the oil flow changes the direction of the following components:
- Barrel (7)
- Pistons (12)
- Shaft (1)
The following components rotate:
- Shaft (1)
- Retaining plate (13)
- Pistons (12)
- Barrel (7)
The following components do not rotate:
- Head (16)
- Case (3)
- Shims (6)
- Retaining ring (4)
Oil from the steering pump flows through port (A) or port (B) into the inlet slot on head (16). Then, the oil flows into the inlet slot in port plate (10) .
Note: Head (16) contains an inlet slot and a outlet slot. The slot that will supply oil to the inlet slot in port plate (10) is dictated by the direction of the turn. Port plate (10) contains an inlet slot and a outlet slot. Also, the direction of the turn determines if these slots in port plate (10) are used as an inlet or an outlet.
Oil that flows through port plate (10) flows into the cylinders of barrel (7) that are over the inlet slot.
The cylindrical heads of pistons (12) are held in the sockets of shaft (1). The heads of the pistons are held by retaining plate (13). The closed end of pistons (12) are positioned in barrel (7). For proper alignment, center pin (8) is at a fixed angle of 28 degrees from the axis of shaft (1) .
The bent axis between pistons (12) and barrel (7) cause seven pistons (12) to move in and out of the cylinders. This forces the rotation of pistons (12), shaft (1), and barrel (7) .
As shaft (1), pistons (12), and barrel (7) rotate, the pistons reach the top dead center. At the same time, the cylinder begins to overlap the inlet slot in head (16) which is open to output pressure from the steering pump. Then, the pistons begin to move downward.
When the pistons reach the bottom dead center, the outlet slot is opened. Piston (12) pushes oil out of the cylinder into the outlet slot in port plate (10). Then, the oil goes through through port (A) or port (B) to the inlet side of the steering pump.
Oil flow into port (A) and oil flow out of port (B) causes shaft (1) to rotate in a counterclockwise direction when you view the steering motor from the drive end. The counterclockwise rotation of shaft (1) causes the machine to turn left when the machine travels forward. The counterclockwise rotation of shaft (1) causes the machine to turn right when the machine travels in reverse.
Oil flow into port (B) and oil flow out of port (A) causes a clockwise rotation of shaft (1) when you view the steering motor from the drive end. The clockwise rotation of shaft (1) causes the machine to turn right when the machine travels forward. The clockwise rotation of shaft (1) causes the machine to turn left when the machine travels in reverse.
Flushing valve (11) provides lubrication and cooling to the internal components of the steering motor. Also, flushing valve (11) removes hot oil from the high pressure circuits of the steering system.
Flushing valve (11) drains approximately 5 L/min (1.3 US gpm) from the low pressure side of the closed loop circuit. The flushing valve consists of two parts: a shuttle valve and a relief valve.
The shuttle valve is shifted by the high pressure side of the closed loop circuit. The shuttle valve opens a path which allows oil on the low pressure side to flow through an orifice and across the relief valve. The pressure drop across the orifice limits the amount of oil that is drained.
When the drain oil leaves the steering motor, the oil is routed to the differential steering unit for lubrication.